Variable inductance device



March 1, 1949. GRIGNQN T AL 2,463,170 VARIABLE INDUCTANCE DEVICE Filed Dec. 9, 1946 E INVENTOR I Lorin .D. Gri non Hilbert G. \Vil xes 8 W65) BY ATTORNEY Patented Mar. 1, 1949 UNITED STATES", PATENT OFFICE VARIABLE INDUCTANCE DEVICE Lorin David Grignon, Los Angeles, and Hilbert Garrison Wilkes, North Hollywood, Calif., assignors to Twentieth Century-Fox Film Corporation, Los Angeles, Calif a corporation of New York Application December 9, 1946, Serial No. 715,036

6 Claims. (Cl. .17l-1192) 1 2 This invention relates to electrical equipment terminates in pole pieces 22 and 23 and is rotatand deals particularly with a variable inductance ably mounted as mentioned above. The opposite device. coil H likewise has an armature designated 24. The invention to be described hereinafter has This armature, unlike the armature of coil 12, been developed to meet several conditions existterminates in pole pieces which are arcuate in ing in the motion picture industry, but in its preform, as shown by numerals 25 and 26 (see Figferred form it may find usefulness in other fields ure 3'). It will be noted that the arcuate memwherever variable inductance is needed. bers 25 and 26 have substantially 'thesame radius One of the principal objects of the invention as the pole pieces 22 and 23 of coil l2 and at the :is to provide a device of the character described same time curve away from the coil l2. This .is wherein the mutual inductance created between for the purpose of providing an incremental "vacoacting coils may be varied to meet predeterriation in the gap between the pole pieces as mined conditions. More specifically, it is an the coil I2 is rotated relative to coil ll. As shown object of the invention to provide an inductance in the drawing, the horns 25 and 25 originate device having the pole pieces of the inductance at ends of the armature 24, and curve in the same coils shaped in a novel way so that the gap bedirection. They could, however, extend in both tween the poles may be varied in any manner directions from the ends of the armature, or in desired, such as logarithmically or linearly, from the opposite direction from that shown, the only a full aiding position to a full opposing position. requirement being that they follow a circum- And, finally, another object of the invention is 30 ference and do not of themselves form a comto provide inductance coils wherein at least one plete circle.

of the coils has pole pieces shaped circumferen- In operation, the two coils are connected in tially so that upon rotation of either of the circuit in any manner desired to achieve the purmutually coacting coils the gap between the pole pose of the oper For full aiding p t pieces may be varied in a predetermined manner. the coils would be set as shown in Figures 1 and 2 Other objects and advantages will become apin Solid lines, that With p p s 2 nd 3 parent as the description proceeds in conjunction Opposite the beginnin s of h arcu te members with the drawing in which: and 26 respectively. In this position the gap Figure 1 is a plan view showing one form my is of minimum width. As the coil I2 is rotated invention may take; 30 to the position shown by dotted lines in Figure 2,

Figure 2 is a side elevation of Figure 1; the gap between the poles is increased in a pre- Figure 3 is a view taken on line 33 of Figure determined manner according to the curve away 2; and from the coil 12 in the arcuate members 25 and Figure 4 is a perspective view showing how the 26. This curvature may be previously calculated two coils may be rotated to regulate the mutual to yield a logarithmic variation in the inductance inductance therebetween. coupling between the pole pieces, or it may be Referring to the drawing, it will be seen that calculated to derive a linear variation, or any we have shown two coils H and I 2 in inductive other predetermined variation desired. If the relation mounted on a base l3. In this instance coil H is rotated farther than the end of the coil II is rigidly mounted on a support M, while arcuate members, the gap increases rapidly and coil I2 is fixed on a shaft I5, which in turn is if the coil 1 I is rotated 180 it is then in a pole rotatably mounted in a support [6 carried on the opposing position. It can thus be seen that as base l3. The shaft l5 may be held against longithe coil l I is rotated relative to coil l2 the inductudinal movement in its support by a collar l1 tive coupling between the two coils may be so and a wheel l8, which may also be used for rotatcontrolled by predetermined calculations that the ing the shaft. As a means of indicating the device could be made to have characteristics espeamount of rotation, we may use a pointer l9 that cially designed for eliminating a very narrow band works over a calibrated arcuate segment 20. The of frequencies which, for instance, has been found conventional arrangement of coils of this nature to be particularly useful in overcoming certain s Suc t t t p b w the D p e s ay faults in speech made by some persons. Other b opened or closed either by moving the coils uses will appear to those versed in the art. away from each other or by rotating one with We claim: respect to the other. Our invention makes use 1. A variable inductan of the rotating coil principle and for this purpose pair of induction coils having their pole pieces the coil I2 is provided with an armature 2| that 5 in mutual inductive relation, one of said coils ce device comprising a having arcuate horns on its pole pieces, and means for rotating one of said coils so that the arcuate horns pass the pole pieces of the other coil to vary the inductive relation between said coils.

2. A variable inductance device comprising a pair of induction coils having their pole pieces in mutual inductive relation, one of said coils having arcuate horns on its pole pieces, and means for rotating one of said coils so that the arcuate horns pass the pole pieces of the other coil and form a gap of varying width therebetween.

3. A variable inductance device comprising a pair of induction coils having their pole pieces in mutual inductive relation, one of said coils having horns on its pole pieces, said horns being arcuate in form and inclined away from the plane of circumference of said horns, and means for rotating one of said coils so that the arcuate horns pass the pole pieces of the other coil and form a varying gap therebetween.

4. A variable inductance device comprising a pair of induction coils having their pole pieces in mutual inductive relation, one of said coils having horns on its pole pieces that are segments of a circumference, and means for rotating one of said coils so that said horns pass the pole pieces of the other coil and form a gap therebetween.

5. A variable inductance device comprising a pair of induction coils having their pole pieces in mutual inductive relation, one of said coils having horns on its pole pieces that are segments of a circumference, and means for rotating one of said coils so that said horns pass the pole pieces of the other coil and form a gap therebetween, said horns extending in the same direction clockwise from said pole pieces.

6. A variable inductance device comprising a pair of induction coils having their pole pieces in mutual inductive relation, one of said coils having horns on its pole pieces that are segments of a circumference, and means for rotating one of said coils so that said horns pass the pole pieces of the other coil and form a gap therebetween, said horns extending in the same direction clockwise from said pole pieces and inclining away from the plane of said circumference in the same direction.

LORIN DAVID GRIGNON. HILBERT GARRISON WILKES.

REFERENCES CITED 1 The following references are of record in the 

